soil experiments?

[Warwick Silvester]

>Does anyone have any ideas for a token lab about soils, fertilizers and
>such?  I'm looking for immediate gratification sorts of experiments or
>observations, not long-term mineral deficiency studies. (The target
>audience is undergraduates with an interest in gardening.)
>
>Kathy Schmid
>schmid at butler.ed
Do you have access to common floating pond weeds such as Spirodela or
Lemna? if so they make excellent subjects for nutrition studies. Take a
variety of  waters eg distilled, tap,  pond,  lake, stream, also from soil
or squeeze some water out of your compst heap. Throw  a set number of
fronds onto  a beaker or jar full and watch them grow, the differences are
dramatic.  For the instant one set it up  a week ahead and ask them to
analyse it. One can work out RGR and C and even Efficiency  if you use
artificial light of known output.
 In similar vein if you take two or three known soils and do a dilution
series with sand ie 1:1, 1:2, 1:5, 1:10, 1:20. then germinate and grow
grass or tomato  or fast plants you can get a pretty dramatic effect. Again
it can be set up ahead  and given to students to analyse. If you use pure
sand you can talk about expt controls  and can work out nutrient supply
capacity of the soil.

Warwick Silvester                      Ph.(07) 838 4613
Dept of Biological Sciences             Fax(07) 838 4324
University of Waikato                     Email WBS at waikato.ac.nz
Hamilton, New Zealand